JPH0758889B2 - Waveform generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform generator that generates a square wave and the like, and more particularly to continuous control of the upper, lower and upper and lower levels of a waveform.

[Conventional technology]

For evaluation of electronic circuits such as hysteresis comparators,
In various electronic measurements, experimentally, a signal waveform having an arbitrary level may be required by controlling only the lower end level or the upper end level of the waveform while keeping the waveform level constant.

[Problems to be solved by the invention]

In order to realize such waveform control with a conventional measuring instrument, it is necessary to control both the output level and the output offset voltage level, and the control for that purpose is to control the output level and the output offset voltage level. It is necessary to operate both knobs, so workability is poor,
It was inconvenient. In particular, in the evaluation of electronic circuits, if the observer concentrates his attention only on the control of such a waveform, the control of other experimental devices is neglected and accurate experimental data cannot be obtained.

In addition, if such a waveform control is used to adjust the level of only the upper or lower end of the output waveform using a conventional measuring instrument, the adjustment must be done manually, and the accuracy of the waveform is Even if we tried to raise the value, we could only expect accuracy as low as several tens of mV.

Therefore, an object of the present invention is to provide a waveform generator that can perform waveform control with high accuracy and is suitable for various electronic measurements.

[Means for solving problems]

As illustrated in FIGS. 1 and 2, the waveform generator of the present invention receives a signal source (signal generator 2) that generates a signal of a constant cycle, receives the signal from the signal source, and A level conversion means (level converter 14) for extracting a coded output corresponding to the level of the signal, a signal conversion means (decoder 24) for converting the coded output from the level conversion means into a switching signal, and a level control input. Variable voltage source (6) that receives and generates a voltage that continuously increases or decreases
And a pulse output that receives a voltage that continuously increases or decreases from the variable voltage source, and switches the voltage by switching with the switching signal from the signal conversion means to intermittently increase or decrease the level. It is characterized by having an analog switch for taking out and (26A, 26B).

[Action]

The signal source generates a signal having a constant period. This signal is converted into a coded output according to the level by the level conversion means. This encoded output is applied to the signal conversion means and converted into a switching signal.

The variable voltage source receives the level control input and generates a voltage that continuously increases or decreases.

A voltage that continuously increases or decreases from a variable voltage source is applied to the analog switch, and a switching signal is applied from the signal conversion means as a switching control input. That is, the analog switch is switched by the switching signal to intermittently increase or decrease the voltage, and as a result, a rectangular wave output whose level intermittently increases or decreases is obtained.

Therefore, according to the waveform generator of the present invention, for example, a square wave whose upper end level continuously increases (or decreases), a square wave whose lower end level continuously increases (or decreases), or an upper end and lower end levels. It is possible to generate a square wave that continuously increases (or decreases).

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the waveform generator of the present invention.

In FIG. 1, a signal generator 2 is installed as a signal source for generating a signal such as a rectangular wave or a sine wave having a specific period.
The signal generator 2 is composed of a sweep generator and a pulse generator. From this signal generator 2, for example, a rectangular wave signal having a constant cycle is applied as a switching control signal to an analog switch circuit 4 provided as switching means. Therefore, the analog switch circuit 4
Is a C-MOS type analog switch,
Switching is performed by the rectangular wave signal from the signal generator 2. In this case, the output signal of the signal generator 2 for the analog switch circuit 4 is set to have an amplitude up to the operable input level of the analog switch circuit 4.

A voltage of a level that continuously increases or decreases is applied to the analog switch circuit 4 from a variable voltage source circuit 6 installed as a voltage source capable of precise voltage control. The variable voltage source circuit 6 can be configured by a programmable programmable voltage source whose voltage level continuously increases or decreases, for example, a voltage source whose voltage level is adjusted by an external microcomputer or the like.

When an arbitrary voltage level is applied to the analog switch circuit 4 by the variable voltage source circuit 6 as described above, the arbitrary voltage level is taken out in an intermittent state by the switching operation of the analog switch circuit 4. That is, the analog switch circuit 4 can obtain a waveform having the signal period from the signal generator 2 and the voltage level set by the variable voltage source circuit 6.

This waveform output is taken out from the output terminal 10 via the buffer circuit 8 as an impedance conversion means for preventing the waveform distortion due to the impedance of the load, and is applied to, for example, the input part of the electronic circuit as an observation target to be evaluated. be able to.

Therefore, according to this waveform generator, the signal generator 2
If the cycle of the generated signal is arbitrarily set and the generation level is arbitrarily set for the variable voltage source circuit 6, the variable voltage source circuit 6 has the signal cycle added from the signal generator 2. It is possible to obtain an increasing or decreasing waveform output with a set voltage level.

In this waveform generator, for example, a rectangular wave signal a as an input waveform from the signal generator 2 to the analog switch circuit 4 as shown in A of FIG.
From the analog switch circuit 4 to the case where only the voltage b of the level which continuously decreases on the positive side with respect to the midpoint level M is applied as shown in FIG. Thus, a waveform output having a level in which only the positive side level decreases according to the level of the voltage b and having the period of the rectangular wave signal a is obtained.

Further, for example, the rectangular wave signal a shown in A of FIG. 2 is continuously generated from the signal generator 2, and the variable voltage source circuit 6 continuously increases on the negative side with respect to the midpoint level M as shown in A of FIG. When only the voltage c of the level which is applied is applied, the analog switch circuit 4 has a level in which only the negative side level increases according to the level of the voltage c as shown in C of FIG. A waveform output with a period is obtained.

In this case, from the signal generator 2, for example, the rectangular wave signal a shown in A of FIG. 2 and from the variable voltage source circuit 6 to the midpoint level M as shown in A of FIG. When the voltage b of a decreasing level and the voltage c of a continuously increasing level on the negative side with respect to the midpoint level M are applied, as shown in B of FIG. 2 from the analog switch circuit 4. As shown in FIG. 2C, a waveform output having a level that decreases according to the level of the voltage b on the positive side and increases according to the level of the voltage c on the negative side and that has the period of the rectangular wave signal a is obtained. .

Therefore, in such a waveform generator, although the usable voltage range is limited by the analog switch circuit 4 and the buffer circuit 8, the variable voltage source circuit 6 uses a constant voltage power source capable of controlling an accurate voltage value. The voltage level at the upper, lower, or upper and lower ends of the output waveform can be precisely and continuously controlled, and can be used for evaluation of various electronic circuits such as electronic measurement.

(Specific Example) FIG. 3 shows a specific configuration example of the waveform generator shown in FIG.

In FIG. 3, the signal of a specific cycle generated by the signal generator 2 is applied to the signal input terminal 12 of the analog switch circuit 4, and is applied from the signal input terminal 12 to the level converter 14 as level converting means. This level converter
The 14 and V _DD terminal 16, V _SS terminal 18, V _EE terminal 20 is provided as a power supply terminal, respectively predetermined voltages V _DD, V _SS, V _EE
INH terminal 22 as a control terminal
Is provided, and in this case, it is set to the L level (ground). The level converter 14 generates a binary code output as an encoded output according to the level of the input signal from the signal generator 2, for example, the rectangular wave signal.

The decoder 24 is a signal converting means for converting this encoded output into a switching signal, and applies this switching signal to the analog switches 26A and 26B as a switching control signal.

The analog switch 26A corresponds to the positive voltage level set by the positive voltage source 6A of the variable voltage source circuit 6 at the level setting terminal 28A, and the analog switch 26B has the variable voltage source circuit 6 at the level setting terminal 28B. It is installed corresponding to the negative voltage level set by the negative voltage source 6B.

In this case, the variable voltage source circuit 6 composed of the positive side voltage source 6A and the negative side voltage source 6B is a programmable voltage level that can be increased or decreased by a level control signal Mc from a microcomputer (not shown) or the like. It constitutes a power supply circuit.

Therefore, in such a waveform generator, as shown in FIG. 2C, when changing only the lower end level of the rectangular wave output, the level setting terminal 28A is fixed to the high (H) level and the negative side is set. Only the voltage source 6B is operated, and its voltage level is continuously changed.

Further, as shown in FIG. 2B, when changing only the upper end level of the rectangular wave output, the level setting terminal 28B is fixed to the low (L) level and only the positive voltage source 6A is set to the operating state. , Change its voltage level continuously.

In either case, since the analog switches 26A and 26B repeat switching in accordance with the signal cycle from the signal generator 2, the signal cycle from the signal generator 2 is provided in accordance with the switching, and the variable voltage source circuit is provided. A waveform having a level of the lower end, the upper end, or the upper and lower ends set by 6 is output from the waveform output terminal 30.

In this embodiment, the buffer circuit 8 constitutes an all-feedback amplifier by the operational amplifier 32 and can prevent the output waveform from being distorted by the impedance of the load connected to the output terminal 10.

Further, in this embodiment, since the variable voltage source circuit 6 is configured so that the output voltage can be controlled by a microcomputer or the like, each of the upper end, the lower end or the upper and lower ends of the output waveform is based on the control input from the microcomputer. The output level can be continuously changed with high accuracy, and highly accurate waveform control can be realized.

〔The invention's effect〕

As described above, according to the present invention, a signal having a constant cycle from a signal source is encoded and then converted into a switching signal, and a voltage having an increasing or fantasy level set by a variable voltage source is converted into an analog signal. In addition to the switch, this analog switch is switching-controlled by the switching signal to intermittently pass the voltage, so that a rectangular wave output having a continuously increasing or decreasing level set by a variable voltage source is generated. For example, a square wave in which the top level continuously increases or decreases, a square wave in which the bottom level continuously increases or decreases, or a square wave in which both the top and bottom levels continuously increase or decrease. It can be generated to realize arbitrary waveform control suitable for electronic measurement such as evaluation of electronic circuits, and especially in evaluation and observation of electronic circuits. It is possible to simplify the work with the improvement of the constant accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the waveform generating apparatus of the present invention, FIG. 2 is a diagram showing the operation of the waveform generating apparatus shown in FIG. 1, and FIG. 3 is a concrete example of the waveform generating apparatus of the present invention. 3 is a block diagram showing an example of such a configuration. FIG. 2 ... Signal generator (signal source) 6 ... Variable voltage source circuit 14 ... Level converter (level conversion means) 24 ... Decoder (signal conversion means) 26A, 26B ... Analog switch

Claims (1)

[Claims] 1. A signal source for generating a signal having a constant period, level conversion means for receiving the signal from the signal source and extracting an encoded output according to the level of the signal, and level conversion means for the level conversion means. A signal converting means for converting the encoded output into a switching signal, a variable voltage source for receiving a level control input and generating a voltage that continuously increases or decreases, and a voltage that continuously increases or decreases from the variable voltage source. And an analog switch for receiving the rectangular wave output whose level is increased or decreased by intermittently switching the voltage by switching with the switching signal from the signal converting means. Waveform generator.